Kaze Hikaru Vol 32

Kaze Hikaru Vol 32 by Taeko Watanabe. A Shojo manga rated Older Teen, published in English by Viz Media.

In 1863 Kyoto, Tominaga Sei disguises herself as a boy and joins the Shinsengumi, the samurai police force, to avenge the murder of her father and brother. Living among swordsmen who can't learn her secret, she finds herself falling for the gifted but gentle Okita Soji.